Abstract
BACKGROUND: MicroRNAs (miRNAs) are noncoding RNAs of 18-25 nucleotides that post-transcriptionally regulate gene expression and are involved in a wide range of physiological and pathological conditions. The β-adrenergic signaling pathway plays a fundamental role in regulation of heart function. The present study was designed to investigate the expression profile of miRNAs and functional implications under conditions of β-adrenoceptor activation or inhibition in rat heart. MATERIAL/METHODS: Hemodynamic parameters were measured to assess heart function in Wistar rats treated with isoproterenol (ISO) or propranolol (PRO). miRNA expression was analyzed by miRNA Microarray and confirmed by real-time quantitative reverse transcription PCR (real-time qRT-PCR). RESULTS: Isoproterenol (ISO, a β-adrenoceptor activator) and propranolol (PRO, a β-adrenoceptor inhibitor) induced differential miRNA expression profiles. Out of 349 miRNAs measured, 43 were upregulated and nine downregulated in the ISO group, while five miRNAs were upregulated and 28 downregulated in PRO group. Among these altered miRNAs in both PRO and ISO groups, 11 were cardiac abundant and 11 showed opposite profiles between the PRO and ISO groups. The recognized anti-hypertrophic miRNAs miR-1, miR-21 and miR-27b, and the pro-hypertrophic miRNAs miR-22, miR-24, miR-199a, miR-212 and miR-214, were upregulated in the ISO group. In the PRO group, pro-hypertrophic miRNA miR-30c was upregulated, whereas miR-212 was downregulated. CONCLUSIONS: β-adrenoceptor intervention alters miRNA expression profile, and miRNAs may be involved in the β-adrenoceptor signaling pathway. Cardiomyocyte hypertrophy is a balanced process between pro-hypertrophic and anti-hypertrophic regulation and involves, at the very least, miRNA participation.